关于MATLAB三阶微分方程的求解和画图
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关于MATLAB三阶微分方程的求解和画图
60=7.18*0.001*dI/dt+1/36.8*30/pi*df/dt*93+1.4*I
8.74/93*(d2f/dt2)*1.15=259*0.001*I
初始条件:
t=0时
f=15/180*pi;
df/dt=11.4028;
I=0
![](http://img.wesiedu.com/upload/6/9e/69ed1a4da57941ae3b97165d7a3ff326.jpg)
60=7.18*0.001*dI/dt+1/36.8*30/pi*df/dt*93+1.4*I
8.74/93*(d2f/dt2)*1.15=259*0.001*I
初始条件:
t=0时
f=15/180*pi;
df/dt=11.4028;
I=0
![](http://img.wesiedu.com/upload/6/9e/69ed1a4da57941ae3b97165d7a3ff326.jpg)
![关于MATLAB三阶微分方程的求解和画图](/uploads/image/z/18689290-34-0.jpg?t=%E5%85%B3%E4%BA%8EMATLAB%E4%B8%89%E9%98%B6%E5%BE%AE%E5%88%86%E6%96%B9%E7%A8%8B%E7%9A%84%E6%B1%82%E8%A7%A3%E5%92%8C%E7%94%BB%E5%9B%BE)
clc;clear
[I,f]=dsolve('60=7.18*0.001*DI+1/36.8*30/pi*Df*93+1.4*I','8.74/93*D2f*1.15=259*0.001*I','f(0)=15/180*pi','Df(0)=11.4028','I(0)=0')
t=0:0.001:0.1;
I=subs(I);f=subs(f);
[AX,H1,H2]= plotyy(t,I,t,f)
xlabel('t')
set(get(AX(1),'Ylabel'),'String','I')
set(get(AX(2),'Ylabel'),'String','\phi')
figure(2)
subplot(2,1,1)
plot(t,I),xlabel('t'),ylabel('I')
subplot(2,1,2)
plot(t,f),xlabel('t'),ylabel('\phi')
图形参见:http://hi.baidu.com/chemical%5Fengineering/album/item/2b240a466f70df2d6a63e5e7.html
![](http://img.wesiedu.com/upload/e/1f/e1fb306bdd8cd3c15bd11c241b61c39a.jpg)
[I,f]=dsolve('60=7.18*0.001*DI+1/36.8*30/pi*Df*93+1.4*I','8.74/93*D2f*1.15=259*0.001*I','f(0)=15/180*pi','Df(0)=11.4028','I(0)=0')
t=0:0.001:0.1;
I=subs(I);f=subs(f);
[AX,H1,H2]= plotyy(t,I,t,f)
xlabel('t')
set(get(AX(1),'Ylabel'),'String','I')
set(get(AX(2),'Ylabel'),'String','\phi')
figure(2)
subplot(2,1,1)
plot(t,I),xlabel('t'),ylabel('I')
subplot(2,1,2)
plot(t,f),xlabel('t'),ylabel('\phi')
图形参见:http://hi.baidu.com/chemical%5Fengineering/album/item/2b240a466f70df2d6a63e5e7.html
![](http://img.wesiedu.com/upload/e/1f/e1fb306bdd8cd3c15bd11c241b61c39a.jpg)